This was startling. Across the world there were reports of unseasonal snow and plummeting temperatures last month, from the American Great Plains to China, and from the Alps to New Zealand. China’s official news agency reported that Tibet had suffered its “worst snowstorm ever”. In the US, the National Oceanic and Atmospheric Administration registered 63 local snowfall records and 115 lowest-ever temperatures for the month, and ranked it as only the 70th-warmest October in 114 years.